Background
The human body has numerous defense mechanisms to keep the airway free and clear of extraneous matter. These include the physical actions of the epiglottis and arytenoid cartilages in blocking the airway, the intense spasm of the true and false vocal cords any time objects come near the vocal cords, and a highly sensitive cough reflex with afferent impulses generated throughout the larynx, trachea, and all branch points in the proximal tracheobronchial tree. However, none of these mechanisms is perfect, and foreign bodies frequently lodge in the airways of children. [1]
Pathophysiology
Children are more prone to aspirate foreign material for several reasons. The lack of molar teeth in children decreases their ability to sufficiently chew food, leaving larger chunks to swallow. The propensity of children to talk, laugh, and run while chewing also increases the chance that a sudden or large inspiration may occur with food in the mouth. Children often examine even nonfood substances with their mouth.
More foreign body aspirations occur in children younger than 3 years than in other age groups, with a peak between the first and second birthdays. However, foreign bodies have been found in the airways of individuals of all ages and sizes. Even relatively immobile infants may aspirate foreign bodies, despite not having the ability to crawl and find things or the ability to pick up objects and put them in the mouth. They have less chewing capacity and higher respiratory rates, so any objects placed in their mouths are more likely to be aspirated than in older children. They also have well-meaning siblings, who may put the wrong foods in the baby's mouth in an attempt to help feed them.
The most common entities aspirated are small food items such as nuts, raisins, sunflower seeds, improperly chewed pieces of meat and small, smooth items such as grapes, hot dogs, and sausages. All of these should be avoided until the child is able to adequately chew them while sitting. Generally, this occurs around age 5 years, with most foreign body aspirations occurring in children younger than 3 years. Small items that are round, smooth, or both (eg, grapes, hot dogs, sausages, balloons) are more likely to cause tracheal obstruction and asphyxiation. Dried foods may cause progressive obstruction as they absorb water.
In a review of 1068 foreign body aspirations in children, the authors found 3% in the larynx, 13% in the trachea, 52% in the right main bronchus, 6% in the right lower lobe bronchus, fewer than 1% in the right middle lobe bronchus, 18% in the left main bronchus, and 5% in the left lower lobe bronchus; 2% were bilateral. [2] In a child in an upright position, the right-sided airways are direct entries from the trachea. The left main bronchus is smaller than the right main bronchus and is slightly angled. In a child in a supine position, material is more likely to enter the right main bronchus.
Epidemiology
Frequency
United States
In the year 2008, foreign body aspiration accounted for more than 17,000 emergency department visits and in 2009 caused 220 deaths in children aged 14 years or younger. [3] Airway foreign bodies are the third most common cause of death due to unintentional injury in children younger than 1 year. [3]
Mortality/Morbidity
Unfortunately, mortality occurs due to acute aspiration, and morbidity can occur due to acute hypoxia during the acute episode or due to chronic lung and airway damage from a long-standing aspirated foreign body. The National Safety Council estimates that 2900 deaths occur annually in the United States because of foreign body aspiration. [4]
Race
No racial predilections are noted.
Sex
Most reviews of foreign body aspiration in children show a slight male predominance.{ref17]
Age
The peak ages during which aspiration of foreign body occurs are the toddler through preschool ages, although foreign bodies have been found in the airways of people of all ages and sizes.
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Aspirated foreign body (backing to an earring) lodged in the right main stem bronchus.
